As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING PREFLIGHT, OBSERVED DISCHARGE LIGHT ILLUMINATED ON CARGO FIRE PANEL. ACFT GROUNDED. PERFORMED FIM 26-23 TASK 802. AFTER DISCONNECTING CONNECTOR FROM NR 1 BOTTLE PRESSURE SWITCH, LIGHT EXTINGUISHED. INSPECTED CONNECTOR WITH NO FAULTS FOUND. INSTALLED THE CONNECTOR AND DISCHARGE LIGHT REMAINED EXTINGUISHED. PERFORMED CARGO FIRE CONTROL PANEL TEST IAW AMM 26-00-02, SYSTEM OPS CHECKED NORMAL. ACFT OK FOR SERVICE.